I have no idea why people submit to these tests. There are only three NHTSA approved tests (walk and turn, one-leg stand, horizontal gaze nystagmus) and they are the only ones with any scientific validity attached. Used in conjunction and properly administered under ideal conditions they are about 91% accurate. But here are lots of “ifs” in there.

Also, the conditions must be ideal and the procedures strictly followed to conduct them accurately. They are never used to help the motorist as the officer takes the most incriminating results and “forgets” the rest. The silly alphabet test, finger to nose, and numbers tests have little to no scientific basis and are subject to the officer’s whims. By the way, most of the sober population cannot say the alphabet backwards since unlike numbers there is no repeating pattern..

“The horizontal gaze nystagmus test is one of three field sobriety tests that comprise the standardized field sobriety test (SFST) battery (the other two tests are the walk-and-turn test and the one-leg-stand test). Scientific evidence establishes that the horizontal gaze nystagmus test is a reliable roadside measure of a person’s impairment due to alcohol or certain other drugs.1

Despite the strong correlation between alcohol consumption and HGN, some trial courts across the country still do not admit the results of the HGN test into evidence. Although the scientific evidence to prove this correlation exists, due to lack of knowledge, inadequate preparation, or limited proffers, the evidence prosecutors have presented to courts has at times been insufficient to satisfy the courts’ evidentiary standards for admitting scientific or technical evidence. As a result, law enforcement officers in a number of jurisdictions use the HGN test only for purposes of establishing probable cause if at all, without securing admission of the test results into evidence at trial. Ultimately, the factfinder never hears the results of the most reliable field sobriety test.”

mespo, my sister was driving home from a funeral of her best friends daughter (who committed suicide) and had been crying almost all day. She was taken to the station for failing these tests, not drunk at all, just emotionally upset.

The cop was soooo good. Funny, polite, . Are you sure this is real? The guy was outstanding. If he could shuffle around that good then he could probably drive well, drunk or sober. The weaving was not his fault, he was trying to pee in a cup. Its all about the bladder.

The great thing about the FST is it isn’t a measure of how much alcohol you consumed. It’s an actual attempt to measure how impaired you are. I think we get too caught up in BAC numbers and don’t pay enough attention to how they affect driving. I don’t care if it’s booze, distractions, narcotics, grief, or tiredness. What impairs you is irrelevant.

The HGN evaluation is a field sobriety test in which the officer attempts to measure the involuntary jerking motion of the eye when the body is exposed to alcohol. Sober folks have this jerking motion (nystagmus) when their eyes move to extreme peripheral angles (like looking extremely left or right) but intoxicated folks have this involuntary eye movement as lesser angles like 45 degrees from center. The three indicators of impairment with a still head are: (1) the eyes cannot smoothly follow a pen moving horizontally; (2) there is distinct jerking at maximum deviation; (3) the onset of the nystagmus occurs at angles within 45 degrees of center. The test is practically worthless because many factors can cause nystagmus besides alcohol.Officers without medical training are incompetent to rule out the other factors like anti-seizure medications, depressants, bright lights and even lack of sleep a la’ shano’s sister.

When I was in college, I had a KHP officer pull me over once and give me the field sobriety test which I passed with flying colors because I hadn’t been drinking. My only crime was being a young guy driving a nice car with three lovely ladies in it (my girlfriend and two of her friends). The stop ended after he asked for the backwards alphabet test. I told him I’d be glad to do so but only in the presence of his duty sergeant and after the officer demonstrated he could do it first. He told me I was free to go. It was on a stretch of highway notorious for the KHP ticketing college students.

I’m excellent at singing the alphabet backwards because when my daughter was little, we had a children’s video which had that as one of the musical numbers. Everything is easier to do when it’s a song. Our brains are wired that way. Gotta be something ancestral, perhaps from hundreds of thousands of years when our proto-human ancestors were warbling around campfires, or maybe as far back as before we evolved from being birds or something.

If I ever get pulled over for suspicion of drunk driving, I’m going to say the alphabet in French. (Which is not such a trick in this bilingual country, although it’s more novel here on the West Coast.) And if I’m actually sober, maybe I’ll do it backwards in French, although “igrec” and “doublevay” don’t have the same meter as the English pronunciations when set to song.